The invention relates generally to electronic modules and particularly to optoelectronic transceiver modules.
Today, communication systems using optical fiber as a means for transmission are widely employed for a variety of purposes ranging from a basic transmission line in public communication channel to a short-distance network such as a LAN (local area network). Since most of the devices connected by these optical fibers are electronic devices rather than optical devices, optical transceivers are commonly placed at the interface between the optical fibers and the electronic devices. An optical transceiver commonly includes an optical transmitter that receives electric signals and converts them into optical signals, and an optical receiver that receives optical signals and converts them into electric signals.
Electrical/optical transceivers, therefore, are designed to be electrically and/or optically coupled to a host device and to a transmission line (to a network, to another device, etc.). Typically, transceivers are packaged in the form of a module that has a host device end and a transmission end. At the host device end, the transceiver module may be mounted on a motherboard of a host device and/or mechanically plugged into a panel that is coupled to the host device. At the transmission end, the transceiver module is mechanically coupled with a signal transfer medium such as an electrical wire or an optical fiber. There are a number of different mechanical interfaces with the optical transceiver which have been used in the past and have evolved into industry standards.
Typically, a transceiver module is physically coupled to the host device with a plastic connector that is soldered onto one end of the printed circuit board (pcb) of the transceiver. The plastic connector is dimensioned to fit with a standard-sized mating structure on the host device. When the transceiver module is physically mated to the host device with this connector, electrical leads and signal ground pins on the transceiver pcb become connected to the appropriate electrical portions of the host device.
While the plastic connector provides a method of electrically coupling the pcb to the host device, it is a source of inconvenience from a manufacturing standpoint. Since the polymeric material that the plastic connector is made of usually cannot withstand the heat that is applied during reflow soldering, the plastic connector has to be hand-soldered onto the board after electronic components are reflow-soldered on to the board. This hand-soldering process, which involves individually hand-soldering each of multiple (e.g., 20) leads to the plastic connector, lengthens the manufacturing process and drives up the cost of a transceiver module. The signal ground pins, which are separate from the multiple leads, are also typically hand-soldered on both sides of the pcb. Thus, the manufacturing process involves turning the pcb upside down to achieve high-quality soldering on both sides of the pcb. This step of turning the pcb upside down also lengthens and complicates the manufacturing process.
Furthermore, since the plastic connector does not block electromagnetic radiation effectively, it allows a significant fraction of the electromagnetic radiation leakage to the host device. This leak is highly undesirable, as electromagnetic radiation is known to interfere with the performance of the host device. This leak of electromagnetic radiation makes it difficult for the transceiver module to comply with certain FCC regulations that require minimization of electromagnetic radiation.
A method of connecting the transceiver to a host device without the above-described disadvantages is desirable.